The Adams Arms Gas Piston System is an end user installed after-market product for Mil-Spec ARs. It will fit on any AR barrel with a .750" or 3/4" diameter at the shoulder where the front sight base sits. The Carbine version will work on barrel lengths from 10.5" to 16" that has an existing carbine gas system. See the FAQ section for the measurements of a carbine gas system.

Reviewed by
4
customer

AA Build,
July 07, 2012

I did my own custom build and after doing a lot of research on the different gas pistons out there, I ended up going with Adams Arms based on the positive reviews on the internet. The only hard/confusing part was setting the spacing on the gas block. Everything else was a breeze. The gas block runs extremely hot so if you were thinking about putting a magpul flip up front sight on there...I'd think twice. Zero FTF and FTE. Cycled 300 rounds and pulled the BCG out for an inspect. No carbon build up what so ever. The hand guard gets all of the carbon build up due to where the gas gets ejected through the piston. Over all, I'm happy with the outcome. Can't wait to get my SD3G trigger and really see what my rifle can do.

By
John from
Cedar Hills, UT

Excellent Piston Kit for AR15 Carbine,
August 05, 2011

After reading message boards, and learning more about piston conversions, the Adams Arms seemed to be the logical choice. It is well made. Conversion was fairly easy, and the only problem I ran into was the getting the spacing on the block correct. Follow the instructions closely, as they explain it and the results are what I had wanted... a clean shooting AR with a cool chamber. The block does get very hot! I have run about 250 rounds through it without a problem. Very good product.

By
Robert C. from
Ogden, UT

If you just have to go piston...go Adams Arms,
December 18, 2010

I purchased this carbine kit for my most recent AR project. Now, I'm not a big fan of the AR becuase I don't like all the mess that's left in the guts of the rifle at the end of a day of shooting. I haven't seen reliability issues with carbon buildup and residue so this isn't a treatise on the virtues of piston over DI. I just like how cleanly the piston system works. Installation of the kit is pretty straight forward and you'll do just fine if you follow the instructions closely. Don't rush through this process. The most difficult part of installation is the receiver bushing that goes into the upper's gas tube hole. Take your time here as getting this part wrong can make you crazy. The craftsmanship of the Adams Arms kit is amazing. Parts fit tightely and are evenly and attractively finished. Make sure you don't use non milspec or cheap parts as this kit needs to be mated to milspec. The bolt carrier is a work of art in and of itself. It's tail end is beefed up in order to mitigate carrier tilt and the drive rod strike face is an integral chunk of steel. This thing looks like it could survive a nuclear blast. I put this together with my AR (brand name of AR witheld)and almost immediately realized that some of my parts were a little bigger/different than milspec. The system was undergassed and over sprung. At this point, Adams Arms' customer service came in to play and I can review it as well. The folks at AA are very helpful and patient and I was able to get my AR running. Even when I broke a part, they sent me a new replacement at no charge. Knowing what I know now and not being very experienced with the AR platform, I would opt for a mid-length carbine and install the AA system on that. And that is my next project. When installed right, the Adams Arms system does what it is designed to do. It operates reliably and cleanly. I still haven't cleaned my upper receiver after 200+ rounds and it looks as clean as when I first bought it. A note to the piston system shopper out there. If you're looking at this system but may be a little intimidated by the prospect of installing it, there are several manufactures out there, including Adams Arms, who are offering complete piston uppers using the AA system. I think that Adams Arms is the way to go. Good luck and good shooting.

By
pdc from
moore, ok

If you just have to go piston...go Adams Arms,
December 18, 2010

I purchased this carbine kit for my most recent AR project. Now, I'm not a big fan of the AR becuase I don't like all the mess that's left in the guts of the rifle at the end of a day of shooting. I haven't seen reliability issues with carbon buildup and residue so this isn't a treatise on the virtues of piston over DI. I just like how cleanly the piston system works. Installation of the kit is pretty straight forward and you'll do just fine if you follow the instructions closely. Don't rush through this process. The most difficult part of installation is the receiver bushing that goes into the upper's gas tube hole. Take your time here as getting this part wrong can make you crazy. The craftsmanship of the Adams Arms kit is amazing. Parts fit tightely and are evenly and attractively finished. Make sure you don't use non milspec or cheap parts as this kit needs to be mated to milspec. The bolt carrier is a work of art in and of itself. It's tail end is beefed up in order to mitigate carrier tilt and the drive rod strike face is an integral chunk of steel. This thing looks like it could survive a nuclear blast. I put this together with my AR (brand name of AR witheld)and almost immediately realized that some of my parts were a little bigger/different than milspec. The system was undergassed and over sprung. At this point, Adams Arms' customer service came in to play and I can review it as well. The folks at AA are very helpful and patient and I was able to get my AR running. Even when I broke a part, they sent me a new replacement at no charge. Knowing what I know now and not being very experienced with the AR platform, I would opt for a mid-length carbine and install the AA system on that. And that is my next project. When installed right, the Adams Arms system does what it is designed to do. It operates reliably and cleanly. I still haven't cleaned my upper receiver after 200+ rounds and it looks as clean as when I first bought it. A note to the piston system shopper out there. If you're looking at this system but may be a little intimidated by the prospect of installing it, there are several manufactures out there, including Adams Arms, who are offering complete piston uppers using the AA system. I think that Adams Arms is the way to go. Good luck and good shooting.

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